Formation of organopalladium complexes via C–Br and C–C bond activation. Application in C–C and C–N coupling reactions

Reaction of [Pd2(dba)3] (dba = dibenzylideneacetone) with two Schiff base ligands (L1 and L2), derived from the condensation of 8-aminoquinoline with 2-bromobenzaldehyde or 2-bromoacetophenone, in refluxing tert-butanol afforded two organopalladium complexes 1 and 2. Crystal structure of complex 1 has been determined by X-ray diffraction studies. Structure of complex 2 has been optimized by DFT method. In both the complexes the imine ligands are coordinated, via C–Br bond activation, as tridentate CNN-donor and the fourth coordination position is occupied by an acetylide ion provided by an outgoing dba ligand via C–C bond cleavage. Both the complexes display intense absorptions in the visible and ultraviolet regions. Both the complexes catalyze C–C and C–N coupling reactions efficiently.

Reaction of [Pd2(dba)3] with two Schiff base ligands (L1 and L2) afforded complexes 1 and 2, where the imine ligands are coordinated as CNN-donors, and an acetylide ion, generated via C–C bond cleavage of dba ligand, is also coordinated. Both the complexes catalyze C–C and C–N coupling reactions efficiently.Figure optionsDownload as PowerPoint slideHighlights
► C–Br bond activation of Schiff base ligands occurs upon reaction with [Pd2(dba)3].
► C–C bond cleavage of dba provides an acetylide ligand.
►  Organopalladium complexes with two Pd–C bonds are formed.
► The Pd complexes efficiently catalyze both C–C and C–N coupling reactions.